Electrical connector



Jan. 3, 1961 H. KELLER ELECTRICAL CONNECTOR Filed Feb. 6, 1958 El V |O\ INVENTOR.

HERMAN KELLER ATTORNEYS ELECTRICAL CONNECTOR Herman Keller, Sidney, N.Y., assignor to The Bendix Corporation, a corporation of Delaware Filed Feb. 6, 1958, Ser. No. 713,636

Claims. (Cl. 339-258) This invention relates to electrical apparatus and more particularly to electrical connectors of the type wherein electrical connections are made by interfitting plug and socket contacts.

One of the objects of the present invention is to provide a socket contact of novel construction for use in readily separable electrical connectors of the pin and socket type.

Another object of the invention is to provide a socket contact having a contact spring on the body thereof which provides more accurate positioning of the contact spring on the body.

A further object is the provision of a socket contact having a contact spring on the body thereof which provides increased holding of the spring against turning about the axis of the body.

A still further object is the provision of a socket contact which lends itself advantageously to the manufacture and assembly thereof in large quantities while assuring the above improvements as to accuracy of location of the contact spring on the body, and the increased securing of attachment and holding of the contact spring on the body.

Yet another object of the invention is the provision of a socket contact having the above advantages which is simple and economical in construction, which is made without the need of undue accuracy of the parts, and which may be readily assembled by existing mechanisms.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. 7

In the drawings, wherein like reference characters refer to like parts throughout the several drawings:

Fig. 1 is a view in plan of one form of socket contact embodying the present invention;

Fig. 2 is a longitudinal sectional view of the socket member of Fig. 1, the section being taken generally on the line 22 of Fig. 1, certain parts being shown in elevation, a fragmentarily shown male or contact pin being shown in elevation inserted in the socket contact;

Fig. 3 is a view in side elevation of the contact spring of the socket contact prior to assembly of the spring on the body of the socket contact;

Fig. 4 is a view in end elevation of the contact spring of Fig. 3, the view being taken from the line 44 of Fig. 3;

Fig. 5 is a view in transverse section through the socket contact, the section being taken along line 5-5 of Fig. 4; and

Fig. 6 is a view in transverse section through the forward end of the contact spring, the section being taken along line 6--6 of Fig. 3.

The present invention represents an improvement in electrical connectors which may be used to advantage in connectors such as disclosed in the application of Swanson and Kokalas, Serial No. 665,471. It will be under- 2,967,288 Patented Jan. 3, 1961 shown in such application, or to use in' connectors of the construction shown herein.

In electrical connectors of the type to which the present invention relates, the socket contact thereof has an elongated body having a longitudinal, contact pin-receiving passage therein. A longitudinally extending contact spring is affixed to the body remote from the forward, open end of the passage, the forward end of the spring communicating with the passage through a slot in the body, whereby the spring may contact a contact pin in the socket.

The contact spring is conventionally attached at its rear end by having wings on the spring bent around the body to form a substantially closed ring, the ring being received within a transverse annular groove in the body. Engagement between the ring and the groove end walls maintains the contact spring from marked movement endwise of the body of the socket contact. Relative rotation between the spring and the body is opposed by the frictional engagement between the ring and the groove, and engagement between the forward end of the contact spring and the body. Such engagement may be that shown in the said Swanson and Kokalas application, wherein the contact spring overlies flat surfaces on the body, or may be that shown in Swanson et al. Patent No. 2,716,744, wherein the contact spring has its forward end lying within a radial slot through the sidewall of the body.

Both such constructions have been found open to improvement, particularly in the smaller sizes of connectors, as regards accuracy of positioning of the contact spring longitudinally on the body when the groove in the body and the ring-forming parts of the spring are made of such relative sizes as to make machine assembly of the socket contact feasible. Specifications for separable connectors require that the contact spring shall not move axially rearwardly upon the insertion of the contact pin into the socket contact. On the other hand, too close a tolerance in the difference between the axial width of the springretaining ring or band and the axial width on the body of the socket contact leads to difficulties in the assembling of the contact spring on such body, particularly when the socket contact is automatically assembled by machine.

The present invention overcomes the above discussed difficulties of prior electrical connectors of the type indicated in a simple, inexpensive manner. It allows the grooves in the body of the socket contact and the band or ring-forming wings on the contact spring to be made with tolerances such that the socket contact body and the contact spring may be assembled rapidly by machine without difiiculty. It prevents rearward travel of the contact spring relative to the body upon the insertion of a pin into the socket. In preferred constructions, the means which prevents rearward travel of the contact spring on the body also aids in maintaining the contact spring from rotation on the body.

In the embodiment illustrated in the accompanying drawings, by way of example, the novel electrical socket contact of the invention includes only two parts-21 body or a socket member 10 and a contact spring 11. In the embodiment shown the body 10 is made in the form of a rigid metallic bar suitably machined, as by drilling and milling, in the manner to be described. The spring 11 is made of sheet metal, and is applied to member 10 in a permanent manner by fastening means which, in the contact shown, is integral with spring 11. The socket member is designed to receive a pin 12 of a plug member so as to make secure, non-arcing contact therewith, while permitting the ready separationof the pin and socket member by movement of the two axially away from each other.

Socket or body member is preferably made from copper alloy bar stock such as brass. One end of body member 10 is drilled to provide a bore 14 for slidably receiving the pin 12 of the aforementioned plug member. The open end or mouth of bore 14 is preferably made bell-shaped at 15 to facilitate entry of the pin 12, which has a diameter only slightly less, usually about .002 to .005", than the diameter of bore 14. The other end of member 10 is likewise drilled and partially cut away at one side to provide a suitable recess 17 in which the end of an electrical conductor may be secured by soldering or other suitable means. Intermediate its ends, member 10 is machined to form two annular grooves 19 and 20, the first of which is utilized in mounting the contact in a resilient support or insert, such as in the manner disclosed in Uline et al. U.S.P. No. 2,563,762.

Groove 20 is utilized, in the manner to appear hereinafter, for mounting spring 11. The body member 10 is provided with an elongated flatted portion 21, shown at the top in Fig. 2, which extends from a position adjacent but spaced from the free end of body 10 rearwardly along the body to intersect the forward edge of groove 20. The fiatted portion 21 is of such radial depth that it lies somewhat radially inwardly of the bottom wall of groove 20 but the upper flat edges 22 lie somewhat radially outwardly of the horizontal diameter of bore 14-. There is thus formed a slot, of less width than the diameter of bore 14, which extends through the wall of such bore. As a consequence, the pin 12 is securely retained against escape from bore 14 at all times, that is, during the insertion of the pin, while it is received in the socket member, and during the withdrawal of the pin from the socket member. The complete annular portion 18, at the entrance or free end of contact member 10, aids in the initial insertion of pin 12, and likewise aids in preventing any tendency of pin 12 to escape laterally from the bore. The fiatted. portion 21 may be made by use of a suitable rotary milling cutter, or otherwise, the cut preferably being taken in a direction transversely of the length of body member 10.

Spring 11 is preferably formed from a blank cut in the form of a. 'i from a suitable hard stiff resilient metal. Various metals may be used for this purpose; one suitable metal is a chrome-nickel alloy known as #93084.

Spring steel may also be used in making spring 12, if

desired.

The central leg 24 of the T-shaped blank constitutes a leaf spring or finger which is preferably slightly tapered in width toward its free end. The free end 25 of finger 24- has a width which somewhat exceeds the distance be tween the confronting inner edges of flatted portions 2-2 of body 10. Preferably the width of finger 24 at no portion throughout its length exceeds the diameter of body 10.

tact, including spring 11, lies appreciably outwardly of the circumference of body 10, even when a pin 12 is engaged in the socket. The free end 25 of spring 11 is bent somewhat upwardly, and inwardly of its tip has a centrally disposed depressed or dimpled portion 26, the inner surface of which projects into bore 14- when there is no pin in the bore of the socket member.

The collar portion 28 of spring 11 is formed of wing portions 27 on the spring blank. The blank is first bent into the contour shown in Figs. 3 and 4, wherein the wings, there designated 27 form the parallel legs of an inverted U, and finger 24 is bent downwardly so that its free end 25 lies markedly below its root.

The spring 11 is applied to contact member 10 by wrapping the wings on the former tightly around body 10 within groove 20. The depth of groove 20 is preferably approximately equal to the radial thickness of collar 28, and the width of the collar is such as closely to fit between the ends of the groove 20. Thus, no part of spring 11 at its point of attachment to body 10 projects radially Thus, when the spring 11 is mounted on the socket member in the manner shown, no part of the socket con beyond the surface of the adjacent portions of such body member. Accordingly, the contact assembly 10, 11 may be removably mounted within a supporting insert in a desirable manner without creating interference with the free action of the spring member. As above set forth the construction is such that the free end 25 of finger 24 does not substantially project beyond the circumference of body 10 when contact end 16 is in bore 14.

By reason of the initial shaping of finger 24 so that its free end lies markedly lower than its root, such free end of finger 24 is in forceable contact with the flat surfaces 22 adjacent the free end of member 10 when there is no contact pin in bore 14. When a contact pin or plug such as pin 16 of plug 12 is inserted in bore 14, projection 26 on the free end of spring 24 will be engaged by the pin and spring 24 will thus be flexed outwardly, placing it under additional tension. The spring thus yie'dably presses the pin 16 again-st the opposite wall of bore 14 to provide good electrical connection. The pressure exerted on the contact pin by the spring is so predetermined that it will neither be too easy nor too difficult to engage and disengage the pin and socket contacts. It will be seen that frictional engagement between the pin 12 and the end 25 of the contact spring tends to cause the spring to follow the pin as the latter is moved.

The socket contact of the present invention employs a novel contact spring employing a resilient tab 29 on the rear edge thereof at the retaining ring or band-forming portion thereof. Preferably tab 29 is located in alignment with the longitudinal axis of portion 24 of the contact spring. In the embodiment shown, tab 29 is formed integral with the contact spring, is generally triangular in plan, and has sharp inner edges 30. In the partially formed blank, shown in Fig. 3, the tab 29 extends rearwardly as an extension of the stock in the central zone of ring portion 28.

The wings 27 on the contact spring blank have an axial width which is somewhat less than the axial length of groove 20., Tab 29 is of such axial length that when the contact spring is placed on the body 10 with the forward edges of wings 2'7 in contact with the forward end wall 31 of groove 20, a substantial part of tab 29 projects rearwardjy of the rear end wall 32 of groove 20. In one connector made in accordance with the invention, the stock of spring contact 11 has a thickness of .012 in., groove 20 has a radial depth somewhat less than this, groove 20 has an axial length of .084, +005, .000 in., wings 27 have an axial length of .082, +000, .005 in., and total axial length of Wings 27' and tab 29 is .092, +002, .002 in.

The contact spring, preliminarily formed as shown in Fig. 4, is applied to body 10 so that wings 27' lie in groove 20 and portion 24 of the contact spring overlies the flatted portion of the body. Thereupon the free ends of wings 27' are clenched around groove 20 by suitable dies, a further die engaging the upper portion of ring or band 28 as the ring is shown in Fig. 2. Such further die is preferably of such length that its rear edge engages the upper zone of the ring at least slightly forwardly of tab 29. The tab 29 is thereby pressed strongly into engagement with the confronting zone of edge 32 of groove 20, the tab being bent upwardly somewhat, as shown in Figs. 2 and 5. The interaction of the tab and edge 32 of groove 20 is such that there is a strong axially forwardly directed component of force which thrusts the contact spring to the right, so that the forward edges of the wings on the contact spring engage forward wall 31 of groove 20. The resilience of tab 22 and of the clenched wings maintains such engagement throughout the life of the socket contact, thereby preventing any substantial axial movement of the contact spring on the body of the socket contact.

The described assembly of the hard contact spring on the relatively soft body 10 causes the sharp inner edges 30 on tab 29 on the former to tend to dig into the outer nopedge of rear wall 32 of groove 20. As a result, the tab has a keying action upon the body, tending to prevent relative rotation between the contact spring and body 10.

Although only one embodiment of the invention has been illustrated in the accompanying drawing and described in the foregoing specification, it is to be expressly understood that various changes, such as in the relative dimensions of the parts, materials used, and the like, as well as the suggested manner of use of the apparatus of the invention, may be made therein without departing from the spirit and scope of the invention as will now be apparent to those skilled in the art.

What is claimed is:

1. An electrical socket contact comprising an elongated metallic body having a longitudinally extending cylindrical bore in a first, forward end thereof, an elongated longitudinally extending slot in the Wall of the body around the bore, said slot communicating with the bore at a zone adjacent the forward end of the bore, a spring contact strip disposed along the body and having a portion adapted to make contact at said zone with a pin inserted in the bore, a split band on the rear end of the contact strip, an outwardly extending shoulder on the rear of the body in axial alignment with the contact strip, the band being bent to embrace the body forwardly of the shoulder, abutment means on the body confronting the forward edge of the band, and means for constantly thrusting the contact strip in a forward direction so that such forward edge of the band contacts the abutment means, said contact strip thrusting means comprising a short, stiff and resilient tab on the rear edge of the contact strip, the rear end of the tab overlying and strongly resiliently engaging the forward edge of the shoulder, the tab being bent to incline radially inwardly in a forward direction from its rear end in that portion thereof overlying the shoulder.

2. A socket contact as defined in claim 1, wherein the tab is generally V-shaped and tapers rearwardly.

3. A socket contact as defined in claim 1, wherein there is a peripheral groove on the rear of the body, the split band has an axial width somewhat less than that of the groove, is disposed in the peripheral groove, the shoulder forms the rear wall of the groove, and the forward wall of the groove forms the said abutment means.

4. A socket contact as defined in claim 1, wherein the body is formed of a relatively soft metal, the tab is formed of a hard stiff metal, and the rear end of the tab is disposed in a shallow mating depression in the outer edge of the shoulder.

5. A socket contact as defined in claim 4, wherein the depression is formed by the pressing of the tab into the shoulder incident to the assembly of the contact strip on the body.

References Cited in the file of this patent UNITED STATES PATENTS Field June 13, 1939 

